CVE-2025-41724 is a vulnerability identified in Sauter's modulo 6 devices, specifically the modu680-AS model. The root cause is a failure to properly handle incomplete SOAP requests sent to the wscserver process, which is responsible for processing web service communications on the device. An attacker can remotely send malformed or incomplete SOAP messages without any authentication, triggering a crash of the wscserver process. Unlike typical service crashes that are mitigated by watchdog processes that restart failed services, in this case, the watchdog does not restart the wscserver, rendering the device's web service functionality unavailable until a manual reboot is performed. This results in a denial-of-service (DoS) condition affecting the availability of the device. The vulnerability is classified under CWE-239, which relates to improper handling of incomplete elements in input data. The CVSS v3.1 score is 7.5, reflecting high severity due to the ease of exploitation (network accessible, no privileges or user interaction required) and the impact on availability. No confidentiality or integrity impacts are noted. The affected product is used in building automation and industrial control environments, where continuous device availability is critical. No patches or firmware updates are currently linked, and no exploits have been reported in the wild, indicating the need for proactive mitigation. The vulnerability was published on October 22, 2025, with the initial reservation date in April 2025.

For European organizations, especially those in industrial automation, building management, and critical infrastructure sectors, this vulnerability poses a significant risk to operational continuity. The inability of the wscserver process to recover automatically after a crash means that targeted attacks can cause prolonged service outages until manual intervention occurs. This can disrupt HVAC systems, lighting controls, or other automated processes managed by the modu680-AS devices, potentially leading to safety risks, increased operational costs, and compliance issues. Since the attack requires no authentication and can be launched remotely, the attack surface is broad, including any exposed network segments. The lack of confidentiality or integrity impact limits data breach concerns, but the availability impact alone can have cascading effects in environments relying on continuous automation. European organizations with large deployments of Sauter devices or those integrating these devices into critical operational technology (OT) networks are particularly vulnerable. The absence of automatic recovery mechanisms increases the operational burden on IT and OT teams to detect and respond to incidents promptly.

1. Network Segmentation: Isolate the modu680-AS devices within secure network zones, limiting exposure to untrusted networks and reducing the attack surface. 2. Access Controls: Implement strict firewall rules to restrict incoming traffic to the wscserver ports only from trusted management networks. 3. Monitoring and Alerting: Deploy monitoring solutions to detect wscserver process crashes or device unavailability promptly, enabling rapid response. 4. Manual Recovery Procedures: Establish and document procedures for manual device reboot to minimize downtime when a crash occurs. 5. Vendor Coordination: Engage with Sauter to obtain firmware updates or patches addressing this vulnerability as they become available. 6. Input Validation Proxies: Where feasible, deploy application-layer gateways or proxies that can validate and sanitize SOAP requests before they reach the device. 7. Incident Response Preparedness: Train OT and IT staff on recognizing symptoms of this DoS condition and responding effectively. 8. Network Intrusion Detection: Use IDS/IPS systems to detect and block malformed SOAP requests targeting this vulnerability. These steps go beyond generic advice by focusing on operational readiness, network architecture, and vendor engagement specific to the affected product and vulnerability.